The best prior art known is U.S. Pat. Nos. 3,391,611 issued to July 9, 1968 to Gavin D. Jenney and 3,270,623 issued Sept. 6, 1966 to K. D. Garnjost et al. The present invention is an improvement upon the monitor valve and system disclosed in U.S. Pat. No. 3,391,611.
Although the system disclosed in U.S. Pat. No. 3,391,611 works extremely well, it has been discovered that differences in the pressures of the fluid utilized in each of the channels, whether command, stand-by or monitor, may affect switching times in the event a failure is detected.
It has also been found desirable to produce a redundant control system maintaining at least as good reliability, response and control accuracy as prior art systems while at the same time making the system less complex, lighter in weight, less costly, and effecting faster switching times upon the detection of a disparity within the system.